1. Field of the Invention
The invention relates to a method of manufacturing a dynamic groove bearing with a first and a second bearing part which are rotatable relative to one another, by which method die bearing parts are provided with cooperating bearing surfaces and the bearing surface of the first bearing part is provided with a groove pattern by means of a metal-removing tool, for which purpose the first bearing part is fastened to a rotatable support of a machine tool, and the metal-removing tool and the first bearing part are displaced relative to one another boy a positioning device of the machine tool while the support is rotating.
The invention also relates to a data storage unit with an information disc and a scanning unit for cooperation with the information disc, which information disc is rotatably supported in a cassette-type housing by means of two dynamic groove bearings provided with spherical bearing surfaces, which housing has two main walls extending parallel to and on either side of the information disc, while an external bearing part of each of the two dynamic groove bearings is fastened to a respective main wall.
2. Description of the Related Art
According to a generally known method of the kind mentioned in the opening paragraph for manufacturing a dynamic groove bearing, the dynamic groove bearing is provided, for example, with a spiraling groove pattern which comprises a number of spiraling grooves provided with equal interspacings, or with a herringbone groove pattern which comprises a number of pairs of grooves arranged in a V-shape with equal interspacings. The metal-removing tool used in the known method is a cutting tool which carries out a number of consecutive planing operations on the first bearing part. During an individual planing operation, the rotatable support with the first bearing part carries out an oscillatory rotational movement and the cutting tool carries out an oscillatory translatory movement such that the cutting tool is repeatedly displaced relative to the first bearing part in accordance with a path which correspondings to an individual groove The individual grooves of the groove pattern are thus consecutively provided in the first bearing part by the known method. The individual grooves formed in this way in general have a constant rectangular cross-section.
A disadvantage of the known method is that the method is time-consuming owing to the oscillatory movements of the support and the cutting tool. Said oscillatory movements have a comparatively high amplitude and a comparatively low frequency because the tool is displaced relative to the first bearing part along the fill length of an individual groove each time, and because the support and the cutting tool are brought to a halt each time in the reversal points of their oscillatory movements and subsequently are accelerated in the reverse direction. In addition the cutting tool cuts in one direction of its oscillatory movement only and is not in contact with the fist bearing part in the reverse direction of its oscillatory movement. A further disadvantage of the known method is that the grooves can be provided with non-constant cross-sections or cross-sections differing from a rectangular shape such as, for example, semicircular cross-sections with great difficulty only, or perhaps even not at all.